Electric oscillatory circuits



ELECTRIC OSCILLATORY CIRCUITS Filed Sept. 14, 1937 ffy f f/g. 2

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Patented Apr. 16, 1940 UNITE SES PATENT orticaN ELECTRIC osciLLA'ronYCIRCUITS Application September 14, 1937, Serial No. 163,799 In GermanySeptember 5, 1936 2 Claims.

As is well known, oscillatory circuits coupled in any manner to anoscillatory system will change their natural frequency whenever thecoupling is varied. In most cases tuning corrections must 6 then be madeby hand in order to give the circuits the previous frequency. This is ofspecial `disadvantage if receivers for wireless telephony and telegraphyare concerned. Here the coupling of the circuits is variable in mostcases in 10 order to provide for changing loudness and selectivity. Forinstance, if here a station already adjusted as regards coupling is tobe readjusted with a View to increasing its separation capability thenat the same time the tuning knob must be 15 actuated in order tocompensate for the detuning caused by varying the coupling.

The invention shows how to avoid such detuning. In accordance with theinvention this result is attained by an automatic correction. In ar- 15rangements as provided by the invention any variation of the couplingentails a variation of the self-inductance or capacity of theoscillatory circuit, the arrangement being such that the detuning of theoscillatory circuit is compensated by an opposing detuning.

The possibilities of carrying out the invention are extremely numerous,as will be understood from the following description, reference being 25had to the accompanying drawing in which Fig. 1 is a Wiring diagramshowing the usual arrangementof an inductive coupling, and Fig. 2 is adiagram illustrating the fundamental conception of the invention asapplied to an inductive a coupling.

By moving coil l away from coil 2, Fig. 1, the resultant inductivity ofthe coil 2 is increased, thus requiring a manual readjustment if, afterthe coupling-variation thus eiected, the oscillatory circuit is to havethe saine frequency as (Cl. Tis-44) before. 3 denotes the capacity ofthe oscillatory circuit.

In the arrangement shown in Fig. 2 the selfinductance of the oscillatorycircuit comprises two coils 4, 5 connected in series. Coil 5 is` smaller5 than coil 4. In accordance with the invention any variation of thecoupling, that is, any movement imparted to coil I causes the couplingeiective between coils 5 and 4 to be varied likewise. In order toperform this the coils il, 5 may be 10 arranged to form a variometerwhich is turned b-y a leverage or some other suitable means wheneverco-il l is moved, or coil 4 may be wound onto coil i, whereby the sameeect as before is obtained with the aid of still simpler means. Equally,it is possible, for instance, to provide for turning a small auxiliarycondenser connected in parallel with the tuning condenser 3.

What is claimed is:

1. In an oscillatory circuit comprising a sel- 15 inductance and acapacity and coupled solely by an adjustable inductive coupler to anoscillatory system, the method of avoiding this circuit being detuned onadjusting this coupling, which method consists in simultaneously andautomatically producing a continuous detuning of opposing character tothat consequent upon a continuous adjustment of the coupling.

2. An oscillatory circuit arrangement comprising an oscillatory circuitincluding a main coupling coil connected in series with an auxiliarycoupling coil and a tuning condenser, another main coupling coil on towhich the first main coupling coil is wound, and means to vary thedisplacement of sai-d main coils with respect to said auxiliary coilwhereby detuning of said oscillatory circuit is continuously compensatedfor during continuous displacement of said main coupling coils withrespect to said auxiliary coil.

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